The present invention pertains to a device for inserting a flexible membrane (e.g., a flexible intraocular lens) into an eye of a patient, and in particular, to a device which enhances the surety of properly loading and advancing the membrane.
Intraocular lenses are implanted into eyes to improve a patient""s vision. The intraocular lens may be a replacement for a natural crystalline lens or designed to function in conjunction with the natural lens. To minimize the size of the incision in the eye, intraocular lenses are ordinarily formed to be flexible. In this way, the lens can be folded or otherwise compressed to pass through a small incision. The intraocular lens is then permitted to expand to its natural size for proper placement within the eye.
Many devices have been developed for the insertion of a flexible intraocular lens into an eye. These devices typically include a tubular member into which the lens is placed and a plunger for advancing the lens through the passage and into the eye. In a number of these inserters, the lens is first folded into a cartridge which is then loaded into a holder with a plunger for advancing the folded lens into an eye. See, for example, U.S. Pat. No. 5,494,484 to Feingold. These devices, however, require several steps to achieve loading and positioning of the lens for advancement into an eye. In other devices, the tubular member containing the plunger directly receives a generally unstressed lens into a staging area of the central passage via a lateral opening in the device. See, for example, International Patent Application No. PCT/US95/09973 to Figueroa et al. In this device, the lens is folded as it is advanced toward the eye by an internal contour of the passage. Accordingly, this device reduces the number of steps needed to load a lens into an insertion device.
When a generally unfolded lens is placed directly into a tubular member, it is usually important for the plunger to engage the lens in a particular manner to effect proper compressing and advancement of the lens into an eye. The plunger may be specially configured to grasp or engage the lens in a particular way. As an example, the plunger in the noted Figueroa application is provided with a slot which is dimensioned to grasp and hold the lens in order to prevent undesired twisting of the lens and to better control the expansion of a lens inserted into an eye. An improper engagement between the lens and the plunger may result in damage to the lens, a loss of control in folding the lens, or an inability to properly advance the lens.
The components of these non-cartridge insertion devices have in the past been composed of a natural, uncolored clear or translucent plastic material. Consequently, the appearance of the plunger tends to blend into the staging area which may result in the surgeon failing to notice the improper position of the plunger. Accordingly, the plunger has at times been inadvertently advanced too far into the insertion device such that the distal tip of the plunger is improperly positioned in the staging area when the lens is loaded. In this position, the lens is set onto the distal tip of the plunger such that the end of the plunger cannot properly engage the lens.
In the present invention, the distal end of the plunger has a visual indicator which provides a contrasting image as compared to the staging area for supporting the lens. The visual indicator thus enables the surgeon to easily see whether the distal tip of the plunger has encroached into the staging area before loading the lens. The visual indicator may consist of providing the distal end of the plunger with a contrasting color. While cartridge type inserters have been produced with different colored plungers, these devices in no way offer a visual indicator for the surgeon during loading of the lens. Rather, the lens in these inserters is loaded and folded in a cartridge separate and apart from the holder containing the plunger.